Does a fan translate a block of air from the fan to another location or away from the fan, or do the blades just set up a longitudinal vibration of air (as it rushes around from the front to the back of the blade as it passes), and the vibration proagates as an air compression....in the same way as if you "push" quickly on a streched slinky spring and the compression travels to the other end ...but the metal of the spring does not move. Similar also to waves on water where the actual water particles move in a circle and do not propagate with the wave itself.
If the fan does just create a vibration that moves the air at a distance but does not move air to the distant place, then why do smells travel with the wave (apparently blown by the fan) and does standing a block of ice in front of the fan move cold air from around the ice to another location...
2006-08-17 00:40:58 · 5 answers · asked by Taoman 2 in Science & Mathematics ➔ Physics
of course...for every action there is an equal and opposite reaction
2006-08-17 00:45:38 · answer #1 · answered by Enigma 6 · 0⤊ 0⤋
A fan translate block of air from the fan to another location or away from the fan.
They also set up a longitudinal vibration of air (as it rushes around from the front to the back of the blade as it passes).That is why sound is heard.
There is nothing in the theory that one of the two alone should take place.
Objects that can float , thrown into the sea, often reaches the shore after some time.
2006-08-17 01:33:55 · answer #2 · answered by Pearlsawme 7 · 0⤊ 0⤋
You could think of a the airfoils/blades as operating on Bernoulli's principle (just like a small airplane wings). In that case, the forward movement of the air would actually be the wake turbulence rushing off the back of the blade as a result of the ruduced air pressure flowing at higher speed combined with the higher air pressure from the forward side of the blade (the back of the blade being the side facing away from the direction of air movement). The blades themselves are moving at a constant speed about the axis/direction of airflow and providing the same amount of airflow, so how would they produce a longitudinal vibration? To achieve a longitudinal vibration, wouldn't you have to be providing a non-constant (i.e. oscillating) airflow? I vote for translation on that one. As you said, how would you feel the cold air from the ice block?
2006-08-17 03:57:10 · answer #3 · answered by mad_g8tr 1 · 0⤊ 0⤋
That is actually a really good question - got me thinking. I think the fan must actually move air because in a plane or helicopter, the blades are actually creating thrust by "pushing" air in the opposite direction to the way we wish to travel. If all they did was act on the air "like" the clinky spring or a wave would you get the desired effect or enough power to propel an aircraft?
2006-08-17 00:49:24 · answer #4 · answered by Anonymous · 1⤊ 0⤋
Whooooooosh. DID YOU SEE THAT?, it went straight over my head.
2006-08-17 00:45:59 · answer #5 · answered by True_Brit 3 · 0⤊ 0⤋